Apparatus for paralleling synchronous machines to maintain reciprocating engines or pumps in synchronism



Jan. 9, 1,934. w, WlLSQN E1- AL 1,942,789

APPARATUS FOR PARALLELING SYNGHRONOUS MACHINES TO MAINTAIN RECIPROCATINGENGINES OR PUMPS IN SYNCHRONISM Filed Jan. 14. 1952 ,2 Sheets-Sheet 2Patented Jan. 9, 1934 PATENTl OFFICE APPARATUS CHRONOUS CIPROCATINGENGINES SYNCHRONISM William Sydney England FOR PARALLELING MACHINES-T0MAINT Wilson, Erdington,

Albert George Emins,

SYN- AIN RE-` OR PUlVIPS IN Birmingham, and Leamington Spa,

Application January 14, 1932, Serial No. 586,542, and in Great BritainJanuary 14, 1931 5 Claims. (Cl. P11-118) This inventionA such enginesarranged by means of synchronous dynamo-electric machines respectivelycoupled to the two engines and i with one another to run interlocked atthe same speed with the direction of rotation of one engine bearing adennite relationship to the direction of rotation of the other engineand with reciprocating parts of the engines at any instant in pre-fdetermined relative positions or at predetermined relative points oftheir cycles of operation. Such arrangements are useful for the purposereducing vibration. The precise way in which the engines should beinterlocked depends on the particular circumstances of the case, but,for example, with a pair o f similar Diesel engines mounted side by sidein aship and arranged symmetrically and having their crank shaftsparallel or substantially parallel with respect to the vertical planeextending longitudinally of the ship and containing the centre ofgravity of the latter itt has gines to run in opposite directions withthe re" ciprocating parts of corresponding cylinders of the respectiveengines at any instant of time similarly disposed so that the powerstrokes for the two cylinders occur simultaneously. 1t has also beenproposed in order to reduce Vibration to fit the twin propellers of avessel so that they rotate directly out ofsynchronism with one an other.For example, 1n the case of four bladed propellers it was suggested thatwhen two blades of one propeller were in a vertical line, two blades ofthe other propeller should be displaced by an angle of 45 from thevertical position. In any case the pair of engines must be synchro-ynized, that is to say they must be caused to run in such a way that thereciprocation or cycle of operations of a piston of one engine occurswith or substantially with a definite phase relationship with respect tothe reciprocation or cycle of operations of a piston of the other engineand the chief object of the invention is the provision of means wherebythis result may readily be obtained with little effort on the part ofthe operator. f

The invention will now be described by way of example vwith reference tothe accompanying diagrammatic drawings in which Figure 1 is a diagram ofconnections showing the invention applied to two Diesel engines adaptedto propel a ship.v the means for operating certain contror 4 mnu-.

contacts being omitted, whilst Figures 2, 3, 4 and 5 illustrate variousmethods of operating the said contacts.

In Figure 1 the engines l'and 2 are coupled directly to the propellershafts 3 and 4 and are arranged to drive them in opposite directions Theengines which are eight cylinder four stroke Diesel engines, are similarto one another and are disposed symmetrically on opposite sides ofcentre line of a ship with their crank shafts parallel to orsubstantially parallel to that centre line, and it is arranged for thecycle of operations of corresponding cylinders of the two engines tooccur synchronously. If desired a higher speed may be obtained, but thenormal, maximum engine speed is 280 R. P. M.

1 and 2 are arranged respectively to drive two alternating currentsynchronous dynamo-electric machines 5 and 6 that may be electricallyconnected and are arranged to operate in such a way that the cycles ofoperation of corresponding cylinders of the respective engines occursynchronously, means being provided which are adapted automatically tosynchronize the machines 5 and 6 whilst corresponding pistons of therespective engines 1 and 2 are at similar points of their cycles ofoperation. In the form illustrated the synchronizing arrangementcomprises means which tend to effect synchronization of the machines 5and 6 when the latter are in a state suitable for synchronization, andmeans which prevent synchronization of the machines unless the movingparts of the engines 1 and 2 are respectively in or near the properrelative positions.

The machines 5 and 6 are in the form of 80 kilowatt 24 pole three phasealternators, the field windings being excited from the busbars 10 and l1connected to a suitable direct current power supply through the switch7, the field rheostats 8 and the slip rings 9.

It is arranged for the synchronization of the alternators 5 and 6 to beeffected by exciting the iield windings of the alternators and byconnecting the alternators in parallel through con1 ductors l2, 13 and14, the connection between the machines first being through a 3-phasechoker 15, which, when the voltages of the two machines aresubstantially equal and the corresponding phase voltages aresubstantially in opposition, is shortcircuited. Theconnection togetherof the two alternators through the choker is effected by means of asynchronizing contactor 16 the `operating coil l'l of which iscontrolled by voltage responsive relay means. The control may be exertedby 2 1,942,789 a single voltmeter relay, but it is preferred to usesynchronizing contactor closes and prevent thi l electromagnet exerts atorque which is, say,5 or position. The synchronizing relay 39 is of theless than the torque exerted by the closing contacter type and thecontacts 38 thereof are electromagnet which tends to rotate the spindlenormally closed, the operating coil 44 of the relay 23 of the relayagainst the force of a controlling being connected across one phase ofthe choker ried by the spindle 23, from a stop 26'to a cosuch that onlywhen the alternators 5 and 6 are a calibrated scale. It may also bearranged for ventive contacts 36 are closed, the alternators the forceexerted by the closing or/and opening are synchronized by closure of therunning con- Inagnet to be adjustable. The two relays are tactor 32.

similarly adjusted and the coil 21 of the closing The preventivecontacts 36 and the mechanism electromagnet of the relay 18 and the coil20 of .for operating them in common with other parts the openingelectromagnet of the relay 19 are of the synchronizing gear may takevarious forms,

25 connected 1n series with one another and on the but in Figure 2 aknife-edged moving contact 46 1 of the opening electromagnet of therelay 18 are them. The contact 46 is mounted on the frame I.'

conductors 13 and 14 joined to two phases of the the easing and meshingwith two similar opposaid alternator. The contacts of the relays 18sitely arranged bevel wheels 50 and 51 also rotatand 19 are connected inseries with 'the operating ablv mounted in the casing 48 and drivenrespec- "1 coil l'l of the synchronizing contacter 16 across tively bythe shafts 52 and 54 having bearings Vthe busbars lo and 1l, the circuitincluding con- 53 and 55 provided on the end of the engine 1. ductor 28,coil 17, conductor 29, contacts 25, 27 The shaft 52 is driven from thehalf-time shaft of relay 18, conductor 30, contacts 25, 27 of relay 56of engine l through mitre gear 57 and the 40 19 and conductor 3l. shaft54 is driven from the half-time shaft 58 11 In operation, when it iswished to effect synof the engine 2 through the mitre gears 59, 62chronization of the alternators 5 and 6 and of and 64, the shaft 60provided with bearings 6l the engines l and 2 the field windings of theon the end of the engine 2 and the shaft 63 vcome the combined force ofthe controlling spring the half-time shafts 56 and 58 respectively. 12'

fers by not more than ve to ten percent from shafts rotate at equalspeeds the casing remains 13) together the alternators 5 and 6 throughthe fore follows that when the shafts 56 and 58 and 3i The synchronizingoperation is completed is in a predetermined position and it is arrangedthrough short-circuiting of the choker 15 by clothat only when thecontact 46 is in or substansure of a running contactor 32 the operatingcoil tially in the said position does it engage the con- 33 of which isconnected across the busbars 10 tacts 47 and allow synchronization ofthe alterand 11, the circuit including conductor 34, coil nators 5 and 6to take place. Once the alterthe contactor to interrupt the circuits ofthe coils 20, 21 of the relays 18 and 19 and to complete a maintainingcircuit for its coil 33. It may be arranged for the moving contact 41 tohave more than one predetermined position, for example, the shafts 52and 54 may be driven to those of the half-time shafts 56 and 58respectively, in which case there will be two diametrically oppositepositions at which two pairs of contacts 47 connected in parallel may beprovided severally at such positions for cooperating with the movingcontact 46.

In Figure 3 the preventive contacts 66 and 67 are respectively mountedon sliprings 68 and 69 severally secured on the ends of shafts 70 and71, from which they are insulated, and cooperating with the brushes 72and 73. The shafts 70 and 71 are in alignment and are driven from thehalf-time shafts 56 and 58 of the engines manner similar to that inwhich the shafts 52 and 54 of Figure 2 are driven, but in this case theshafts 71 and 70 are driven in the same direction. The gearing is soarranged that the shafts 7l and 70 respectively run at the same Thecontacts 66 and 67 are arranged at a definite relative position of theshafts 70 and 71 to engage one another and clearly such position of theshafts 70 and 71 corresponds to a definite relative position of theshafts 56 and 58. Furthermore, the contacts 66 and 67 are so positionedon the shafts 70 and 71 that when the contacts engage the engines l and2 are in similar positions and corresponding cylinders firesimultaneously. For the sake of clarity the contacts 66 and 67 are shownmounted on spring arms but in practice one of the contacts would bemounted with its contact face fiush with the surface of a disc orcylinder of insulating material carried by the driving shaft so that theother contact would press against and move smoothly over the surface ofthe disc or cylinder and the contact face. Once the alternators 5 and 6are synchronized the contacts 66 and 67 move together in engagement withone another.

In Figure 4 mounted on but insulated from the half-time shafts 56 and 58are the sliprings 75 and 74 respectively cooperating with the brushes 81and 80, and provided with the arms 77 and 76 carrying the brushes 79 and78. The brushes 78 and 79 move over the inner surfaces of the axiallyextending insulated segments 83 of the commutators 85 and 86.

Each commutator is provided with thirty segments and the successivesegments 82 of the commutator 85 proceeding in a clockwise direction arerespectively connected by conductors 84 to successive segments 83 of thecommutator 86 proceeding in a counter-clockwise direction. It followsthat when the brushes 78 and 79 are on interconnected segments 82 and 83there is a circuit between the brush and the brush 81 through slipring74, arm 76, brush 78, the said segments and a conductor 84, brush 79,arm 77 and slipring 75. The arms 76 and 77 are so positioned relativelyto the half-time shafts 58 and 56 that such circuit is made only whenthe reciprocating parts of corresponding cylinders of the engines are inor approximately in similar positions in their cycles of operations. Itwill be understood that vthe preventive contacts may be closed when thesaid parts are, say, `within plus or minus 71/2% of the predeterminedrelative positions. The brushes 78 and 79 are arranged to engage onesegment 82 or 83 before leaving another segment and it therefore followsthat when the engines are running in synchronism the circuit through thepreventive contacts is maintained.

In Figure 5 the armatures 90 of the auxiliary generators 87 and 88 aremounted on the ends of the half -time shafts of the engines 1 and 2. Thegenerators similar to magnetos and comprise permanent magnets 89 andtwo-pole shuttle type armatures 90 the windings 91 of which areconnected through sliprings 92 and 93 windings 91 of the generators 87and 88 are connected through the brushes 94 and 95 in series with thewinding 97 of a relay provided with preventive contacts 98 and in serieswith a current limiting choke 96, the arrangement being such that whenthe corresponding cylinders of the two engines are firing simultaneouslythe armatures 90 are in similar positions and the voltages of the twogenerators 87 and 88 in the circuit of the winding 97 are equal andopposite. The moving contact 98 is biased to the close position, but ifthe moving parts of the two engines are far removed from their correctrelative positions in their cycles of operation, since the voltages ofgenerators 87'and 88 are not opposite in through the coil 97 and effectsopening of the contacts 98 and the contacts are maintained open parts oftheengines including the half-time shafts 56 and 58 are near theirproper relative positions when the contacts reclose.

In operation, when the ship has been manuvred out of port, the enginesare synchronized merely by exciting the field windings of thealternators 5 and 6 and adjusting the engine throttles until the enginespeeds are nearly the same but one engine is very slowly overtaking theother 1/3 of .a cycle per second greater, whereupon the engines havingattained or nearly attained the condition in which their reciprocatingparts and half-time shafts 56 and 58 are in similar positions thealternators automatically 'synchronize and cause the engines With anarrangement using protective contacts as shown in Figure 2, for example,the operator may, if he wishes, expedite the synchronizing process bywatching the moving contact and by slightly speeding up an engine untilthecontact is nearly in the permissive position and by then adjustingthe throttle and engine speed to that most favourable for effectingsynchronization.

Conveniently a synchronizing lamp ork similar device is provided andalso an ammeter or wattmeter for indicating the current or power iiowbetween the alternators 5 and 6 and when the alternators and engineshave synchronized the operator may adjust the throttle of an engine toensure that the engines are properly sharing the load. One greatadvantage of coupling together the engines electrically as describedabove is that power may be transferred electrically from one shaft tothe other and this operates to equalize the shaft speeds in a storm whenthe load on one shaft may tend suddenly to vary greatly.

The alternators may be utilized for supplying electrical power forauxiliary services, and in such case their capacity may be suitablyincreased. The power may be withdrawn directly or through convertingapparatus and suitable voltage regulating means will generally beprovided.

Suitable protective arrangements will, of course. be provided forprotecting the apparatus.

The invention may be ing part of the electric machines when they arerotating at approximately th N. SYDNEY ALBERT GEORGE EMMS.

